1. Field of the Invention
This invention relates to an iced food shipping container and to a composite nonwoven article for use therein which comprises superabsorbent polymer particles for absorbing aqueous liquids that form during shipment. More particularly, the invention concerns such a container wherein the liquid-absorbing article is in the form of a composite nonwoven fabric comprising a hydrophilic outer fabric that encloses a nonwoven web in which superabsorbent polymer particles are distributed.
2. Description of the Prior Art
Containers for use in shipping fresh food on ice are known in the art. A typical container has two internal compartments separated by a perforated support member. In use, the upper compartment contains ice, in which or on which fresh food is placed. Often, the lower compartment contains a pad which is intended to absorb any aqueous liquids that are released from the food or result from melting of the ice. Trapping of the aqueous liquids is especially important when fresh food, such as fish, live shellfish and the like, is being shipped. If some of the ice melts during shipment, the resulting liquid water plus aqueous liquids from the food itself can contaminate and spoil the food, if the liquids are not properly handled.
Several types of liquid-absorbing pads have been used to absorb and immobilize the aqueous liquids encountered during shipping of iced fresh foods. To increase the absorbing efficiency of the pad, absorbent particles of hydrocolloidal polymer (hereinafter referred to as "superabsorbent polymer" or "SAP") have been incorporated into pads that have been used commercially in iced food shipping containers. Such superabsorbent polymers are known. For example, U.S. Pat. Nos. 4,654,039 (Brandt et al), 3,670,731 (Harmon) and 3,669,103 (Harper et al) disclose such SAP particles being mixed with various fibrous and pulp materials for use in disposable diapers, sanitary napkins, incontinent pads, facial wipes and the like. When wetted with water, the SAP forms hydrogel, which is capable of holding water amounting to many times the dry weight of the dry SAP particles.
A known SAP-containing pad used in commercial iced food shipping containers comprises SAP powder contained between two nonwoven fabrics sealed together at their edges to form a pouch for the SAP powder. Some of the particles of the powder are adhered to the inner surfaces of the fabrics. However, because most of the SAP powder is loose within the pad, the powder often migrates to and concentrates in one part or near a sealed end of the pad. Such mal-distribution within the pad can lead to "gel blocking", a phenomenon characterized by rapid swelling of SAP particles in regions of high particle concentration. Such rapid swelling can prevent the other SAP particles from absorbing liquid, either because groups of the other particles become encapsulated with hydrogel, or because swollen hydrogel particles clog the pores of the outer fabric of the pad.
Another SAP-containing commercial absorber pad for use in iced food transportation employs a perforated plastic film which surrounds a lofty fabric that has SAP powder adhered to its surfaces. This commercial pad also has shortcomings. The film does not readily wick aqueous fluids, gel-blocking often occurs and the perforations in the film can become clogged quite easily. Efficient use of the SAP in the pad can thereby be significantly limited.
Accordingly, it is an object of this invention to provide a liquid-absorbing article for use in iced food shipping containers that eliminates or greatly reduces the above-described shortcomings of currently used commercial absorber pads.